What would be the approximate net charge of the peptide shown below at pH=6.4 ? To facilitate answering this question, assume that the N-terminal aminium group has a pKa of 8 , the C-terminal carboxyl group has a pKa of 3.5, and that the ionizable side chains have pKas as follows: Asp=4.0, Glu =4.0, His =6, Cys =8.4,Tyr=10, Lys =10, and Arg=12.5. Also, assume that if the pH is at least two units above or below the pKa of a particular group, then that group is completely unprotonated or protonated, as the case may be. Report your answer to the nearest hundredth